The invention relates to a rotor spinning machine and, more particularly, to a rotor spinning machine having plurality of working stations and a bobbin supplying device extending along the machine, wherein at least two service units supplying the working stations with bobbins are supplied by the supply device and wherein the rotor spinning machine comprises a control device for controlling the service units.
Service units are used on rotor spinning machines and can be moved on guide rails on the longitudinal sides of the rotor spinning machine. Starting spinning after a thread break and supplying the spinning stations of the rotor spinning machine with bobbins belongs to the tasks of the service devices. In order to keep the stoppage times of the spinning stations as short as possible in the event of a thread break or bobbin change, a plurality of service units are used on a rotor spinning machine, for example two service units on each longitudinal side of the machine.
German Patent Publication DE 199 05 856 A1 describes a rotor spinning machine, which, between its end frames, has a plurality of working stations, which are arranged on the two longitudinal sides of the machine. These working stations each have a spinning mechanism and a downstream winding mechanism and are supplied by a plurality of service units during operation. A service unit is requested and positioned at the working station for a bobbin change at a working station. From the bobbin magazine, a bobbin is requested, which is transported by means of a conveyor belt to the working station. The service unit has a device, with which the bobbin delivered can be removed from the conveyor belt. The bobbin is then positioned in the winding station in the operating position.
When the service unit operating further away from the bobbin magazine requests a bobbin first and, before the bobbin has arrived at this first service unit, the second service unit positioned closer to the bobbin magazine also requests a bobbin, it may occur that the bobbin intended for the first service unit is removed from the conveyor belt by the second service unit. Delays occur as a result, which can lead to undesired long stoppages of working stations.